The body of a mobile device, such as a cellular telephone, a laptop computer, a tablet computer, a personal digital assistant (PDA) or the like may include one or more metal parts and one or more plastic parts. For example, a polyphenylene sulfide (PPS) part may be insert molded or overmolded to an aluminum part to form the body of a mobile device. Although it may be desirable to form the entire body of a mobile device from metal such that the body is both strong and has a consistent and aesthetic appearance, many mobile devices are configured in such manner as to require the body to include some combination of plastic and metal parts. For example, a mobile device may include one or more antennas disposed within the body. In order to permit the transmission of radio frequency (RF) signals to and from the antennas, the portion of the body that is aligned with the antennas may be formed of plastic. Additionally, the body of some mobile devices may include a portion having a complex geometry that may be difficult, costly or otherwise inefficient to fabricate from a metal. Thus, the portion of the body of a mobile device that has a complex geometry may also be formed of plastic.
The inclusion of plastic parts within the body of a mobile device may introduce a number of issues. From an aesthetic standpoint, the plastic part may appear different than the metal part, thereby potentially reducing the attractiveness of the mobile device. For example, the plastic part may form a stripe, seam or window between metal parts of the body of the mobile device. Such a seam may be undesirable in some instances in which a seamless body is aesthetically preferable. Additionally, a body that includes a plastic part in the form of a stripe or seam may disadvantageously permit the metal parts that are physically separated by the plastic part to sometimes be inadvertently electrically connected by a user of the mobile device while carrying or holding the mobile device. Further, the surface of the plastic part may be softer than the surface of the metal part with this difference in the feel of a plastic part relative to a metal part being potentially disconcerting to the user of the mobile device.
To reduce the likelihood that a softer plastic part will be scratched, the plastic part may be coated separate from the metal part, such as by painting or the application of a hard coating to the plastic part, prior to combination with the metal part. As a result, the plastic parts and the metal parts may exhibit a color difference and/or the plastic parts and the metal parts may not be perfectly aligned with one another such that there is a step or offset exists between the plastic and metal parts, thereby detracting from the aesthetic appeal of body of the mobile device.
A non-conductive vapor metallization (NCVM) coating may be applied to the body of a mobile device having both plastic and metal parts so as to provide a metallic appearance to the plastic parts, thereby creating a more uniform appearance. However, the NCVM-coated plastic parts will still have a different tactile feeling than the metal parts and, in instances in which a top coat is been applied to the NCVM-coated plastic parts, the visual appearance of the plastic parts may no longer be metallic, that is, the plastic parts may no longer have a consistent appearance with the metal parts. Further, the surface hardness of an NCVM coating is less than that of metal, thereby potentially leading to increased wear of the NCVM coated plastic part which may, in turn, further increase the visual differences between the metal and plastic parts such that the resulting body of the mobile device eventually becomes less attractive.